The field of the present invention relates to trailers used for overland transport of goods. More particularly, the present invention relates to adjustable wheelbase trailers.
Commercial tractors and other types of trucks transport freight or goods using trailers such as flatbeds, platform trailers, enclosed vans, container transport chassis or other suitable types of trailers. Many of these transport vehicles have adjustable wheel assemblies that allow the operator to change the trailer or vehicle wheelbase. The wheelbase must be adjusted for a variety of reasons including decreasing the turning radius and improving weight distribution to meet Federal axle-weight requirements.
As illustrated in FIGS. 1 and 2, a tractor trailer used 10 includes a front support strut assembly 20 and an adjustable wheel assembly or xe2x80x9cbogiexe2x80x9d 25 joined by at least two frame rails 15. The front support 20 and rails 15 form a main trailer or chassis structure to which the bogie 25, is slidably attached. The bogie 25 comprises at least one, and usually two axles with four wheels rotatably mounted to each axle. When the operator wants to change the trailer 10 wheelbase, the operator changes the location of the bogie 25 relative to the main trailer structure.
The bogie 25 has bogie lock pins 35 receivable into bogie lock pin holes 30, which extend through the rails 15. Accordingly, when the bogie lock pins 35 are inserted and locked into the boogie lock pin holes 30, the bogie 25 is securely positioned and held.
The bogie 25 location is usually moved by locking the wheels, retracting the bogie lock pins 35 from the bogie lock pin holes 30 and using the tractor to slide the trailer frame rails 15 on the bogie rails 60. Once the bogie 25 has been positioned in the desired location, the bogie lock pins 35 are re-inserted into the bogie lock pin holes 30. Typically, at least two bogie lock pins 35 are used, one for each rail 15.
Referring to FIGS. 2-4, a bolster strip 45 is welded around the bogie lock pin holes 30 to reinforce the frame rail 15 and bogie lock pin holes 30 against the loads imparted through the bogie lock pins 35 and into the frame rail 15 by the bogie 25. When inserted into the bogie lock pin holes 30, the bogie lock pins 35 only engage a thin ring of frame rail 15 material that comprises the perimeter of the bogie lock pin hole 30. Substantially all of the loads encountered by the bogie 25 are transferred to the trailer 10 through this thin ring of frame rail 15 material.
The bolster strip 45 is generally welded to the outside of the frame rail 15 with the frame rail aperture 31 having a larger diameter than the bogie lock pin hole 30. This creates a bolster lip 50, illustrated in FIGS. 3-4. As a result, when the bogie 25 is repositioned to change the trailer wheelbase, the bogie lock pin 35 oftentimes contacts the bolster lip 50 and fails to properly engage the bogie lock pin hole 30. When the bogie lock pin 35 fails to properly engage the bogie lock pin hole 30, an extremely unsafe situation is created because the bogie 25 is no longer positively attached to the frame rails 15.
In addition, moisture accumulates between the bolster strip 45 and the frame rail 15, causing corrosion around the bogie lock pin holes 30 and decreasing the structural strength and integrity of the frame rails 15 and the bolster strip 45. Also, because substantially all the bogie 25 loads are carried by the thin ring of bolster strip 45 material, the bogie lock pin hole 30 perimeters become oval, which introduces play or slack in the bogie 25, increasing the possibility of disengagement of the bogie 25 from the trailer 10. Also, corroded frame rails 15 can fail when the trailer 10 is loaded with cargo, and this failure can occur while the trailer 10 is operating in highway traffic, possibly resulting in a serious accident.
Therefore, there exists a need for an adjustable wheelbase trailer that can withstand the loads imparted by a bogie, without deformation of the bogie lock pin holes, and can also consistently ensure positive engagement of the bogie to the trailer.
In order to overcome the deficiencies with known, conventional bogie location systems, an adjustable wheelbase trailer is provided. Briefly, the present invention solves the problem of a bogie lock pin failing to properly engage a bogie lock pin hole. In addition, the present invention solves the problem of bolster strip corrosion and the subsequent structural deformation of the bolster strip, bogie lock pin holes and the underlying frame rail.
An adjustable wheelbase trailer constructed according to the present invention provides a way to consistently engage the bogie lock pins into the bogie lock pin holes. Moreover, the present invention removes the bolster strip thereby eliminating corrosion of the trailer frame rails and bogie lock pin hole perimeters, and in such manner trailer life is increased and manufacturing costs are reduced.
Broadly, the present invention provides a method to remove the bolster strip while maintaining sufficient bogie lock pin hole strength to prevent deformation. In addition, the invention improves engagement of the bogie lock pins in the bogie lock pin holes.
More specifically, one embodiment of the invention forms a flanged bogie lock pin hole in a trailer frame member by punching an hole in the trailer frame member, deforming a perimeter area of the hole, and extruding the deformed perimeter area so that the perimeter of the extruded hole is larger than the punched hole. The extruded material thus forms a flange which the bogie lock pin engages.
Another embodiment of the invention comprises a trailer having an adjustable wheel assembly, the trailer comprising at least two laterally spaced frame members. A plurality of openings are located in the frame members, with each opening having a flange section structured to receive an adjustable wheel assembly bogie lock pin.